urethra and vagina, which are close together. They resemble the labia in Man, and differ from those in the other Primates.
Brain.—It has been pointed out by Dubois (167) that the volume of the brain relatively to the size of the
body is almost identical in Tarsiits and Nyctictbux. There are, however, important differences in the form and structure of the brain, and the following list contains the most important points :—
(1) The olfactory bulbs are relatively less than in the Lemurs, and relatively larger than in the higher Primates.
(2) The visual cortex is relatively larger than in the Lemurs, and less complex than in the higher Primates.
(3) The cerebral hemispheres are short and wide, they overlap the cerebellum more than in the Lemurs, and their surfaces merely show a small suprasylvian sulcus on each side.
(4) The association centres are much smaller than in the higher Primates.
(5) The corpus callosum is small.
(6) The cerebellum has large paraflocculi.
(7) The pons varolii is small and the trapezium is exposed.
Organs of Special Sense.—When the organs of special sense in the three Primate sub-orders are compared it is evident that Tarsius is intermediate between the Lemuroidea and Anthropoidea. In the first place the olfactory sense is poorer than in the Lemuroidea and better than in the Anthropoidea; and the reduction in the snout has allowed the eyes to come more to the front of the face, with the result that the visual fields overlap.